Antifroth discharging means for centrifugal separators



Aug- 2, 1938. H. o. LINDGREN 2,125,453

ANTIFROTH DISCHARGING MEANS FOR CENTRIFUGAL SEPARATORS Filed March l2, 1955 2 Sheets-Shee'c l Allg- 2, 1938- H. o. LINDGREN 2,125,453

ANTIFROTH DISCHRGING MEANS FOR CENTRIFUGAL SEPARATORS Filed March 12, 1935 2 Sheets-Sheet 2 Patented Aug. 2, 1938 UNITED STATES PATENT OFFICE ANTIFROTH DISCHARGING lMEANS FOR CENTRIFUGAL SEPARATORS Application March 12,

1935, Serial No. 10,633

In rSweden June 30, 1934 11 Claims.

It is known to use in centrifugal separators discharge devices or fskimmers which project intol the rotating mass of liquid and by means of which the liquid can be taken out under pressure from the centrifugal bowl. In connection with the treatment of liquids which are not to any substantial degree unfavorably influenced by the admiXing of air, considerable latitude is allowed in selecting an operative construction. It is, for instance, practicable to utilize a tube, projecting intothe liquid, the orifice of which is directed towards the tangential movement of the liquid. But in the treatment of liquids in which the admixing of air causes a formation of froth, as for instance milk, a device of this type is not eiiicient, as strong whirls are formed at the tube which cause great quantities of air to be intimately mixed with the liquid. With the object of preventing these whirl-movements it has been known to use a disc-shaped skimmer provided with channels opening at the circumference of the disc. The rotating mass of liquid encloses the circumference and covers part of the disc adjacent its periphery, for the purpose of preventing air from being mixed with the liquid streaming into the disc through the aforementioned channels. The disc should be positioned in a special chamber rotating with the bowl and communicating with the separating chamber. If the discharge or skimmer device is intended to take out skimmilk from the bowl, the special chamber must be arranged to communicate with the separating chamber in the neighborhood of the periphery of the bowl. Experience has shown, however, that even with this device it is very diiiicult to discharge the liquid in a frothless state. Irregular iiows of liquid are caused at the free level of the liquid in the special chamber in which the skimmer device is 40 positioned, as the inner part of the rotating mass of liquid is on the one side influenced by the frictional forces from the stationary skimming device and on the other side by similar forces from the rapidly rotating wall of the 45 chamber. On the inner liquid surface, which is in contact with the air, forces are also at play, originating from the air, which here of course has a rather irregular movement. In order to obtain a complete absence of froth it has proved necessary to work with great overlapping of the skimming device by the liquid, that is, to work with a thick layer of liquid inside the outer edge of the skimming device. Owing to the great speed at which a centrifuge rotates, a measure of this kind is undesirable, as it causes a considerable power consumption.

The present invention relates to an arrangement by means of which a frothless discharge can be secured that is not open to the objections specified. A characteristic feature of the invention is that adjacent both surfaces of the skimming device more or less near their outer edges an inwardly directed flow of liquid is maintained, the velocity of which is sufficiently great to prevent the air from being conveyed from the inner surface of the liquid into the special chamber from which the skimming device removes liquid.

In the accompanying drawings, which illustrate four of different possible embodiments of the invention- Fig. 1 is a vertical sectional view of the upper part of a centrifugal bowl and of the associated construction for skimming and froth prevention.

Fig. 2 is a similar view of a modification.

Fig. 3 is a fragmentary section on line 3--3 of Fig. 1.

Fig. 4 is a vertical sectional view, similar to Figs. 1 and 2, of another modification.

Fig. 5 is a vertical sectional View, similar to Figs. 1, 2 and 3, of still another modification.

Fig. 6 is an enlarged vertical sectional view of a part of Fig. 5.

Referring first to Fig. 1: Communicating with the peripheral part or sludge chamber of the centrifugal bowl 2 is an outiiow channel 4 discharging into an annular chamber 3 into which the peripheral part of the skimming device eX- tends. The skimming device may comprise a disc-shaped element 5 which may be similar in construction to a turbine wheel; that is, it may be provided with channels 6 formed by wings (see Fig. 3) arranged more or less tangentially. These channels converge to a central channel, or system of channels, l, from the exit ends of which the skimmed liquid is discharged into the usual collecting vessel (not shown). The skimmer, for a short distance from its periphery inward, is positioned, measured vertically, close to the members 8 and 9 (which are secured to rotate with the bowl and form between them the chamber 3), leaving throttled passages l0 which connect chamber 3 with chambers Il and l2. Chamber Il is formed between member 8 and the skimmer 5. Chamber I2 is formed between the skimmer 5 and member 9. Beneath chamber l2 is a froth extinguishing chamber I3.

vv4 into the chamber 3, whence it is dischargedunder pressure by the skimmer 5.

*surface or the liquid-to the outer edge of 'the kimrnerI cannot roccur. By reason of the throttled passages'll] between chamber 3 and chambers II and I2, there is maintained an inwardly directed flow which is comparatively small in volume but comparatively great in velocity( Provision must of course be made for maintaining the desired circulation of liquid. The simplest arrangement would be to allow the liq-J uid entering chambers II and I 2tovesc'apeiromfy the bowl and be collectedin aspecialJcollecting vessel-possibly that for the separated light liquid; e. g. cream. If oompletefabs'ence 'offiro'th" is not required andthe inward rate of ow ycan be maintained sufficiently low, Asuch an arrange-V ment is permissible; 1When substantially'com' plete absence 'of frothfisdesir'ed or required'fthe n inward velocity of the liquid must'fnecessarily be`4 30" kept lso high' that special provision'inust vbe made' to establish circulation in ,tl'ie"bovvl`.V ,IYo r eff ct thisthe skimmer Eisfprovided .channels I5, Whieh'may be'formed in the wings 60 (see Fig.` 3),-, and connect chambers II and I2,Whil`efop`e'nings "l5 `connect.' chamber I2 fand'r the fffrothfextin?.

guishing" chamber I3 and openings-I4y V,connect chamber ,i3 and channels lil, Chamber,v `I3"is vided with radially extendingconveyorl wings'll'. Chambers Inland i2! are not proyideci with conveying Wings. f Owing to the'bralfzing4 action ,of the` skimmer, which may be increased', ifdesired, by providineit with Wings the liquid in chambers I I' andi lj2;'

,will rotate ata speed 'lovverf` than the `speedV 'of distant from theeeteref the bowl than thepinlner 'ming devices at the skimmer' and operating;in;A 'the chambers l I and I 2 may conduct liquid thererotation of the bowl, The liquidgin these chiama bers will be intimatelymixed with-air, forreaso'n's hereinbefore explained, so that its spe'cic gravityl L" is lovverthan that of the heavier separated liquid', e. g., skimmilk. Such lower speoificlfgravity and thereduced tangential 'speed 'cause theV inner'level ofthe liquid; indicated by the linen'in'chambers II and I2 torrbe inside` the lev'elof the liquid in' the separatingcha'mbe'r4 of the bowl, the position' of which determines'the pressure in therchannels. 4. All of thel Wings I'l`inthe froth extinguishing chamber I3 rotate with the bowl and. there is thusr no tendency therein to frothformation; the tendencybeing to separate air from the frothy rnilkw entering through lopenings I5. Suitable'means should be provided for the removal ofthe sep' arated air from the 'froth 'extinguishing vchamber" I3, as, for example, a central channel 3|,"betw`een chamber i3'and a Space outsidethebowl. The

.ffull conveying in the chamber' I3 'and "thehiglfik speciiicf-gravity` of 'thejliqu'id' therein' cause itsl inn-v A ner surface, indicated by the line y, to be lmore' surface of thefliquid indicated by linear, in chaine Vbers I'I and vlI2, therebyallowingfow 'of'lliquid from'chamberIZ into chamber I3. Y K y v Other means for effecting thenecessary vcirculay tion of liquid may be adopted. "Ihusspecial skimfrom intotheffrothlextinguishing chamber I3, as hereinafter described. y

VvThe skimming device is shown and described as-arran'ge'dtin'a chamber which communicates thegperipheral part of the body, and there- `5 :foreihandles the heavier separated component. .The lighter separated component may Ybe discharged in any suitable way, as, for example, through one or more outlets 32 extending through the bowl wall andone or more of the centralizing 10 ribs 33; or such lighter separated component, also or instead, may be discharged by means of a second skimming device, which need not be shown and described, since the arrangement need merely substantially duplicate that described for dis- 15, charging the heavier separated component.

The skimmer need vnot be of the type hereinbefore described. It may .be constructed in any suitablemar'iner, as shown, for example, in Fig. 2..

In ,this modication, the skimmer comprises two 2@ spaced apart'discs 20 and '2 I`,.whichf extend into the annular chamber 3. Enclosed between these: discs `arespiral vanes or` wings 22, forming between them channelsv directed "toward'the gential direction of the flow of liquid. Inside g5 chamberI 43`is a number of wingsZllxedtothev bowl wall. The spiral shaped channels Aformed byV the wings 22 ziok not ext'endto the peripheriesor the discs 2i)l andl ZI. Their outer edges terminate" ata considerably 'shorter radial.distance from 'the 301" center of the bowl. v The'conve'yr Wings 24 extnd` in vvard almost. ,to 'the mouths', of the 'channels formedV by Wings 22;- rI 'he object offthis arrange-'-y men-t is to obtain aslow .af tangential speed as possible oi the discharging liquid 'at the'entrance T35' openings of the skimming V4'chanifielsk lltfis not suflicient merely to locate rthese openings.. at a' Considerable distance rwithin' the peripher'es 'of uisesizt and 2 i'. 1 The liquid flowing inward to- Ward 'these channels tends to'.retairwitsenergyf0y andjtherefore, onV its'way'finward it'ftendsfto increase its tangential speed.` The effectwof 'the conveyor wings '24 yis to -prevent vthe liquid from increasingits'fangular speed` and thus reduce the tangential, speed'to the 'same value as the tanfgerr-g`y u eating with chambers I I land I2 and correspondf55A ingf'to openings Iii of Fig.A 1, ,which chambersv` collect liquidfo'wing inward through the throttles and discharge it into the yfroth extinguishingv chamber i3.

Fig. 4 showsanother modication in which two' discs 35 vand, 35 "forming a, skimmerr are spaced so close together thatP the reductionpf rotary velocity is causedby frictionpan'd wings v(such asmV i) are not Hrequired between them.

I have hereinbefore referredtothe; i565;

of providing special v,skimming v v l devices operatingcf in chambers II and lI2 `for Figs.'5 an'df illustrate sueh a possible arrang ment. The skimming device may be the same 20"* j forming between them and the'skimmingdevice spaces that at their outer' ends open into chamy.

bers II and I2 and that are connected one with 75j i the other at their inner ends by channels 42 formed, like channels I6, in the skimming device. At its inner end, as well as at its outer end, the lower space communicates with chamber l2. In both spaces are radial wings 43 which may extend throughout the radial dimensions of the spaces. These wings prevent rotation of the liquid in these spaces land hence eliminate any centrifugal force. The liquid can therefore flow freely toward the center. As the entrance to these spaces is nearer to the center than the entrances to channels 6, any frothy milk will be deflected into these spaces and will eventually reach the froth eliminating chamber I3. In Fig. 6 arrows show the direction of circulation.

What I claim and desire to protect by Letters Patent is: v

1. A centrifugal separating machine comprising a revoluble outer chamber adapted to contain a body of separated liquid and from which such liquid is intended to be removed, a relatively stationary skimming device extending into said chamber and adapted to overlap the body of liquid therein, two inner revoluble chambers one above and one below the skimming device and into which is adapted to flow liquid not removed by the skimming device, means providing restricted liquid outilow passages between the inner chambers and the outer chamber including communicating means for liquid between such two inner chambers.

2. A centrifugal separating machine comprising a revoluble outer chamber adapted to contain a body of separated liquid and from which such liquid is intended to be removed, a relatively stationary skimming device extending into said chamber and adapted to overlap the body of liquid therein, two inner revoluble chambers one above and one below the skimming device and into which is adapted to ilow liquid not removed by the skimming device, means providing restricted liquid outflow passages between the inner chambers and the outer chamber including' channels formed in the skimming device to allow ow of liquid from one inner chamber to the other.

3. A centrifugal separating machine comprising a revoluble outer chamber adapted to contain a body of separated liquid and from which such liquid is intended to be removed, a relatively stationary skimming device extending into said chamber and adapted to overlap the body of liquid therein, two inner revoluble chambers one above and one below the skimming device, means providing restricted liquid outowV passages betweeny the outer chamber and the inner chambers, a froth extinguishing chamber communicating with one of the inner chambers, relatively stationary discs extending into said inner chambers and providing liquid flow spaces between them and the skimming device and inwardly through which liquid is adapted to flow, and wings substantially preventing rotation of liquid in said spaces.

4. A centrifugal separating machine comprising a centrifugal bowl, a stationary skimming device, an enclosure for the skimming device, said enclosure being revoluble with the bowl and the peripheral part of which is adapted to receive separated liquid, the skimming device being discshaped and having a peripheral inlet adapted to penetrate the body of separated liquid in the enclosure, said enclosure being contracted adjacent the entire peripheral part of the skimming device to an extent sufficient, in operation, to generate and maintain adjacent the peripheral part of the skimming device, and outside the inner level of liquid in the enclosure, an inwardly directed ow of liquid sufliciently strong to prevent air from being conducted from the inner surface of the liquid to the peripheral inlet of the skimming device.

5. A centrifugal separating machine in accordance with claim 4 wherein the skimming device comprises liquid receiving means and discs on opposite sides of the liquid receiving means, and wings in and revoluble with said enclosure extending into the space between said discs and terminating near said liquid receiving means.

6. A centrifugal separating machine comprising a centrifugal bowl, an enclosure revoluble with the bowl and adapted to contain a body of separated liquid, said enclosure comprising an outer an annular part of the skimmer adapted to restrict the flow of liquid between the inner and outer portions of the enclosure so that a limited volume of separated liquid will, in operation, flow inwardly into the inner part of the enclosure at high velocity and thereby prevent air from being conducted from the inner surface of the liquid in the enclosure to the peripheral inlet of the skimming device.

'7. A centrifugal separating machine comprising a centrifugal bowl, walls forming an enclosure communicating with the interior of the bowl and adapted to contain a body of separated liquid and from which liquid is intended to be removed, a relatively stationary disc-shaped skimming device within the enclosure having a peripheral inlet part adapted to penetrate said body of liquid, said walls being widely spaced from the major part of the skimmer but closely approximating the outer surface of the skimmer adjacent its peripheral part to thereby divide the enclosure into outer and inner portions and afford between them restricted passages for iiow of liquid at high velocity from the outer portion of the enclosure to the inner portion thereof and thereby prevent air from passing from the inner surface of the liquid to the inlet of the skimming device.

8. A centrifugal separating machine comprising a revoluble enclosure adapted to contain a body of separated liquid and from which such liquid is intended to be removed, a relatively stationary disc-shaped skimming device with a peripheral inlet extending into said enclosure and adapted to overlap said body of liquid and discharge liquid therefrom, means to generate and maintain adjacent the peripheral part of said skimming device an inwardly directed iiow of liquid outside the skimming device sufciently strong to prevent air from being conducted from the inner surface of the liquid to the skimming device, a froth extinguishing chamber, and means affording communication between the inner portion of said enclosure and said chamber and between said chamber and the peripheral portion of the enclosure.

9. A centrifugal separating machine comprising a revoluble enclosure having an outer portion adapted to receive a body of separated liquid and from which such liquid is intended to be removed, a relatively stationary skimming device extending `tic'na'rydisc-shajg'ied skimming device ywith a peripheral inlet extending into said enclosure and vadapted tor overlap's'aid body,7 of liquid and discharge liquid therefrom, means vto generate and umaintain adjacent the peripheral part of said skimming device an inwardly directed flow of liquid Aoutside the skimming device sufficiently 'strong to prevent air from being conducted from they inner surfacezof the Vliquid to the skimming device, and means to separateufrom the liquid that has owed inwardly outside the skimming device; airfentrainedtherein-and to return the air# fre'liquid 'te the outer peripheral portion of the enclosure.

* A centrifugal separating machine comprisin g a revoluble 'enclosure adapted to contain a body of separated liquid and from which Asuch liquid fis intended to be removed, a relatively statinary disc-shaped skimming device with a vvperipheralinlet extending into said enclosure and adapted to 'overlap said body of liquid and dischargegliqtd therefrom, means to generate and maintain adjacent the peripheral part of said skirrimi'ngV device an inwardly 'directed new of liquid outside `the skimming device suiciently streng to prevent air from being ccnducted from the inner surface of the liquid to the skimming device, said skimming device comprising two vspaced apart discs and wings conned between vthe fdi'src's and 'shaped to provide liquid receiving 'channels who'seout'er 4 en dsare at a substantial d tancejinsidethejperipheries ofthe discs, and 4w gsin tlieperipheral part of said l'enclosure reat'a'ble 'with thejbowl and extending inward between the peripheral parts of the discs.

HANS onor1 LINDGREN. 

